The trajectory of a golf ball is mainly determined by the initial conditions of velocity, direction, and spin rate.
Many systems in the golf ball launch monitor category which is intended to measure spin rate depend on applying marks to the surface of the golf ball. This limits the utility of these systems due to the effort required and makes it unacceptable when a launch monitor is used for example on the tee at a professional golf tournament where ball marking is not possible.
Thus, it would be beneficial to provide a means to reliably and accurately measure the spin rate of an unmarked ball. It would be further beneficial to provide a means to measure the spin rate of an unmarked ball using Doppler radar.